Trench isolation structures are used in semiconductors to improve performance of semiconductor devices. More specifically, deep trench isolations are provided to prevent leakage between an N-Well structure and a P-Well structure. In an N-Well structure, a source and a drain of a PFET may be made of boron and in a P-Well structure, a body of an NFET may also be boron. As a result, a PFET adjacent to the body of the P-Well structure may cause parasitic leakage. Similarly, in a P-Well structure, a source and a drain of an NFET may be made of arsenic or phosphorous, and in an N-Well structure, a body of the PFET may also be arsenic or phosphorous. As a result, an NFET adjacent to the body of the N-Well structure may also cause parasitic leakage. That is, adjacent P-Well and N-Well structures suffer from junction leakage, i.e., parasitic leakage.
As such, the respective well structures should be isolated from one another. Accordingly, deep trench isolations (DTI) are used to prevent inter-well leakage. More specifically, deep isolation trenches are used to prevent parasitic leakage between an N-Well structure and a P-Well structure. However, forming deep trench isolations requires many complex and costly fabrication processes, including masking and alignment steps.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.